abaqus-geometry

# Abaqus Geometry Skill Create parts, assemblies, and import CAD files for finite element analysis. ## When to Use This Skill **Route here when user mentions:** - "create a box/beam/plate/bracket" - "draw geometry", "make a cylinder/tube" - "import STEP/IGES file" - "extrude", "revolve", "create assembly" - "position the parts", "build a component" **Route elsewhere:** - Meshing the geometry -> `/abaqus-mesh` - Defining materials/sections -> `/abaqus-material` - Applying loads or BCs -> `/abaqus-load`, `/abaqus-bc` - Full analysis workflow -> `/abaqus-static-analysis` ## Key Decisions ### 1. How to Create Geometry? | Shape | Approach | |-------|----------| | Box, plate, beam | Sketch rectangle + extrude | | Cylinder, tube | Sketch circle + extrude | | Pipe, disc, shaft | Sketch profile + revolve | | Complex/existing | Import STEP/IGES | | Quick prototype | Primitives | **Decision guidance:** - Simple prismatic shape? -> Sketch + extrude - Axisymmetric part? -> Sketch + revolve - Existing CAD model? -> Import STEP file ### 2. Where to Place Origin? | Origin Location | When to Use | |-----------------|-------------| | Corner (0,0,0) | Asymmetric parts, easier coordinate math | | Center (0,0,0) | Symmetric parts, rotation about center | ### 3. Part vs Instance Coordinates | Context | Use | |---------|-----| | Geometry creation, section assignment | Part coordinates | | BCs, loads, sets, finding faces | Instance/assembly coordinates | **Important:** After creating an instance, use `instance.faces.findAt()` not `part.faces.findAt()`. ## What to Ask User If unclear, ask: - **Shape type?** Box, cylinder, imported CAD? - **Dimensions?** Length, width, height in mm - **Origin location?** Corner or center? - **Import file available?** Path to STEP/IGES? - **Features needed?** Holes, fillets, chamfers? ## Workflow ### Step 1: Create Model and Part Create the model container, then a 3D deformable part. ### Step 2: Define Geometry Choose approach based on shape: - **Sketch + Extrude:** Draw 2D profile, extrude to 3D - **Sketch + Revolve:** Draw profile, revolve around axis (360 degrees for full solid) - **CAD Import:** Open STEP/IGES, create part from geometry file ### Step 3: Add Features (Optional) Add secondary features if needed: - Cut holes using cut extrude - Round edges with fillet - Partition cells for BC/load regions ### Step 4: Create Assembly Instance Create root assembly with Cartesian datum, then create instance from part. ### Step 5: Create Sets and Surfaces Create named sets/surfaces on **instance** (not part) for: - BC regions - Load application surfaces - Design regions (for optimization) ## Finding Entities Two methods to locate faces/edges: 1. **findAt()** - Exact coordinates (point must be ON the entity) 2. **getByBoundingBox()** - Tolerant box search (better for automation) Combine multiple entities with `+` operator. ## Common Pitfalls | Problem | Cause | Solution | |---------|-------|----------| | "Sketch is not closed" | Gap in sketch entities | Ensure lines connect to form closed loop | | "Cannot find face at coordinates" | Point not exactly on face | Use bounding box or verify coordinates | | "Part has no cells" | Sketch not extruded | Call BaseSolidExtrude or similar | | "Instance already exists" | Duplicate name | Use unique name or delete existing | ## Validation Checklist Before proceeding to mesh/analysis: - [ ] Part created with correct dimensions - [ ] Geometry is watertight (no gaps) - [ ] Instance created in assembly - [ ] Sets created on **instance** for BC/load regions - [ ] Partitions added if needed for region selection ## Units All dimensions use consistent units (mm-tonne-s-N-MPa): - Length: mm - Coordinates: mm ## Code Patterns For API syntax and code examples, see: - [API Quick Reference](references/api-quick-ref.md) - [Common Patterns](references/common-patterns.md) - [Troubleshooting Guide](references/troubleshooting.md)